The present invention is suitable for an ion current density measuring method and the measuring instrument, and a semiconductor device manufacturing method. Here, the method and the instrument are the ones for measuring the current density of ions launched into a wafer and its distribution, which are one of the plasma characteristics in the plasma processing for an etching, a CVD, or the like.
In the manufacturing of a semiconductor device, and in a plasma-utilizing wafer processing apparatus in particular, the current density of the ions launched into the wafer and its distribution are important factors for determining the properties of the processing, e.g., the rate and the uniformity of the etching or the deposition, and damages of the components.
As a method of measuring the current density of the ions, there has been known a technology referred to as a probe method. This method has been described in, e.g., Shinriki Teii, xe2x80x9cBasic Plasma Engineeringxe2x80x9d, 1st ed. (published on May 30, 1986), Chap. 3. In the probe method, a probe is inserted into a region where the ion current density is to be measured, and positively charged ions are led selectively into a measuring unit by an electric voltage applied to the probe, thereby measuring the ion current density.
Also, concerning a technology of making a contrivance to the wafer so as to measure the ion current, JP-A-8-213374 can be cited, for example.
Although the above-described technology has an advantage of making it possible to measure the ion current density at an arbitrary position within the plasma, the ion current density measurement by the insertion of the probe was a difficult task. This is mainly because, in a plasma processing apparatus used for the mass production of the semiconductor devices, there exists a fear that the probe insertion causes metal contamination or foreign substances to be produced, or, it is required to provide a mass-producing apparatus with a port for the electrical wiring.
In the technology disclosed in JP-A-8-213374, in principle, the above-described probe is built and incorporated in the wafer. This condition requires that the electrical wiring for the voltage control or the signal fetching be set from the wafer to the outside of the plasma processing apparatus. Accordingly, the technology cannot be said to be appropriate for the mass-producing apparatus.
The object of the present invention is to measure the current density of the ions launched into the wafer without installing the electrical wiring through the plasma processing apparatus or without making the special contrivance to the wafer or a wafer-supporting member, thereby providing the ion current density measuring method and the measuring instrument and the semiconductor device manufacturing method which are suitable for the mass production.
In order to accomplish the above-described objects, in the present invention, there is provided the wafer including a semiconductor or a conductor provided on an insulator, an insulator formed on the semiconductor or the conductor and having a region the thickness of which has been made locally thin, and a 2nd conductor provided on the insulator, one of the semiconductor or the conductor and the 2nd conductor having a 1st region from the surface of which a substantially entire solid angle is formed, the other having a 2nd region a solid angle formed from the surface of which is made smaller than the 1st region, wherein the wafer is exposed to the plasma, and a voltage is applied to the semiconductor or the conductor and the 2nd conductor so as to measure a time that will elapse until the insulator undergoes a dielectric breakdown, then determining the ion current density from a charge and an area exposed onto the surface of the 2nd conductor, the charge being needed to cause the insulator to undergo the dielectric breakdown in correspondence with the voltage.
On account of this, one of the semiconductor or the conductor and the 2nd conductor has the 1st region from the surface of which the substantially total solid angle is formed, and the other has the 2nd region the solid angle formed from the surface of which is made smaller than the 1st region. As a result, electrons and the ions reach the 1st region by the same flux on average. Meanwhile, in the 2nd region, the flux of the high kinetic-energy ions exhibits an isotropic behavior, thus becoming larger than the flux of the low kinetic-energy electrons. This makes the electric potential of the 2nd conductor positive with reference to that of the semiconductor or the conductor, causing an electric current to flow through the region in the insulator the thickness of which has been made locally thin. In addition, the wafer is exposed to the plasma, and the voltage is applied to the semiconductor or the conductor and the 2nd conductor so as to measure the time that will elapse until the insulator undergoes the dielectric breakdown. This, further, allows the ion current density of the plasma to be determined from the charge needed to cause the insulator to undergo the dielectric breakdown and the area exposed onto the surface of the 2nd conductor. Consequently, it becomes possible to measure, on the wafer, the current density of the ions launched into the wafer without giving the special contrivance to the wafer or the wafer-supporting member, thereby allowing the measuring method of the ion current density to be made suitable for the mass production.
Also, in the present invention, there is provided the wafer including a semiconductor or a conductor provided on an insulator, an insulator formed on the semiconductor or the conductor and having a region the thickness of which has been made locally thin, and a 2nd conductor provided on the insulator, one of the semiconductor or the conductor and the 2nd conductor having a 1st region from the surface of which a substantially total solid angle is formed, the other of the semiconductor or the conductor and the 2nd conductor having a 2nd region a solid angle formed from the surface of which is made smaller than the 1st region, wherein, after the wafer has been exposed to the plasma for a fixed time, a voltage is applied to the semiconductor or the conductor and the 2nd conductor in a state of being not exposed to the plasma, thereby determining a charge that causes the insulator to undergo a dielectric breakdown, and then determining the ion current density from the charge and an area exposed onto the surface of the 2nd conductor, the charge being needed to cause the insulator to undergo the dielectric breakdown in correspondence with the voltage.
Moreover, in the present invention, there is provided the wafer including a semiconductor or a conductor provided on an insulator, an insulator formed on the semiconductor or the conductor and having a region the thickness of which has been made locally thin, and a 2nd conductor provided on the insulator, one of the semiconductor or the conductor and the 2nd conductor having a 1st region from the surface of which a substantially total solid angle is formed, the other of the semiconductor or the conductor and the 2nd conductor having a 2nd region a solid angle formed from the surface of which is made smaller than the 1st region, wherein, after the wafer has been exposed to the plasma for a fixed time, the capacitance-to-voltage characteristic of the semiconductor or the conductor and the 2nd conductor is measured, and an electric current flowing through the region that has been made locally thin is calculated from the capacitance-to-voltage characteristic that was measured before the wafer has been exposed to the plasma, then determining the ion current density from an area exposed onto the surface of the 2nd conductor.
In addition, in the present invention, there is provided an ion current density measuring instrument for setting a wafer at a predetermined position in a plasma processing apparatus so as to measure the ion current density at the time when the wafer is exposed to the plasma, the instrument having the wafer including a semiconductor or a conductor provided on an insulator, an insulator formed on the semiconductor or the conductor and having a region the thickness of which has been made locally thin, and a 2nd conductor provided on the insulator, one of the semiconductor or the conductor and the 2nd conductor having a 1st region from the surface of which a substantially total solid angle is formed, the other having a 2nd region a solid angle formed from the surface of which is made smaller than the 1st region, wherein an electric current flowing through the region in the insulator the thickness of which has been made locally thin is measured, thereby determining the ion current density.
Furthermore, in the present invention, an ion current density distribution in the plasma processing apparatus is measured so as to ascertain whether or not the distribution measured is in compliance with an ion current density distribution that becomes a criterion, then manufacturing the semiconductor devices.
On account of this, when manufacturing the semiconductor devices, the ion current density distribution is measured so as to ascertain whether or not the distribution measured is in compliance with the ion current density distribution that becomes the criterion. Accordingly, in the mass production of the semiconductor devices, there exists no necessity for destroying the mass-produced products to check them.
Still further, in the present invention, there is provided a wafer including a semiconductor or a conductor, an insulator formed on the semiconductor or the conductor and having a region the thickness of which has been made locally thin, and a 2nd conductor provided on the insulator, one of the semiconductor or the conductor and the 2nd conductor having a 2nd region a solid angle formed from the surface of which is made smaller than another region, wherein the wafer is exposed to a plasma, thereby measuring the ion current density of the plasma so as to manufacture the semiconductor devices.
Even further, in the present invention, there are formed on a wafer a 1st region into which ions and electrons are launched and a 2nd region into which the ions are launched but the electrons are not, wherein the wafer is exposed to a plasma, then measuring the ion current density of the plasma taking advantage of the 1st region and the 2nd region, thereby manufacturing the semiconductor devices.